Engine cooling using the heater settings

[markweatherill]

I've always had cars with 'manual' controls for the heater, that is, levers that move the air flaps and water valve. So I keep the heater at COLD to help the engine warm up and that's always seemed to work.
My current car, a 2007 Mitsubishi, has the heater and A/C controlled by buttons and I am not at all sure there is a water valve. I think this is one where the coolant always flows and the heater simply diverts air over the core or not (and it does take a long time to warm up in the morning so I can't really tell if the heater position matters, and I think it doesn't).

But definitely, I've always had the heater as my last resort to combat overheating.

[California98Civic]

If the engine is very hot after a climb but not hot enough to trigger the radiator fan and if the heater has been selected for "hot" already so that coolant is circulating through the heater core, when I cut the engine to coast a long straight or downhill I can take all the heat out of the heater core in under one minute by running the cabin fan at top speed setting, temp selector on hot. Air starts out hot, but gets cool in 30 seconds or so. When I next restart the engine, that small amount of cooled coolant begins to circulate in the system again as the water pump starts-up, bringing the overall coolant temp down slightly.

[ps2fixer]

Ironically I get the oppsite effect. When my car is cold, putting the selector on hot seems to heat it up quicker (judging by distance travled before it hits 130F for 4th gear to kick in). I always leave the fan off. Factory my car came with a 180 thermostat, and I installed a 195 one, so maybe the hole in the thermostat is too big and not letting the engine get up to temp quickly. The 180F thermostat was stuck open, can't really comapair sadily when it always ran around 130-140F lol.

Now if I turn the fan on, or allow fresh air in while selected to hot, it will cool the engine pretty quickly down to around 185F from ~198-203.

[eco_generator]

The heat is going somewhere, that's for sure. When the car is moving the cowl vents are pushing air through your ducts. The heat is probably coming out in a non-intrusive manner with the windows down. I can heat my car to a comfortable level on 45 degree mornings with the windows up and the heater set to warm or hot, no fan.

[ps2fixer]

Originally Posted by eco_generator

The heat is going somewhere, that's for sure. When the car is moving the cowl vents are pushing air through your ducts. The heat is probably coming out in a non-intrusive manner with the windows down. I can heat my car to a comfortable level on 45 degree mornings with the windows up and the heater set to warm or hot, no fan.

I do the same thing by setting my air setting to fresh air in. Normally have to turn it down 1/2 way or it will get too hot, and this works all winter long, but the fan does get the heat transferred faster lol. It don't help to clear windows that much though, very slow reaction time.

[krrcan]

Possible explanation:
1) Lower air pressure below the car.
2) Higher pressure above the hood.

1&2 ->
Air flowing from the air intake on the hood, through the element and into the engine compartment and out below the car.

[zingaro]

Wow, day 2 on the forum and ive picked up some great info. Never considered the heater into the cooling cycle but I too am thinking the newer vehicles have no valve to eliminate water from entering the heat radiator just a flap to control and divert the air.

In the 12 ram cargo van you hear a lot of flappin (and not just from the wife) when u go pushin the air controls.

SO: the lite is on. I have noticed a low inlet air temp even with a lot of frontal blockage but maybe a duct that could regulate where that bypass air went. IE a way of regulating inlet air temp from the inside with the heater controls. Who d thunk it ?????? z